A planet-hunting astrograph built in the 1920s to seek out the so-called "Planet X" beyond Uranus.

This Arizona observatory is famous for investigations into Martian life, and as the place humans first spotted Pluto.

The final resting place of the businessman-turned-astronomer who helped discover Pluto stands near his observatory.

Ancient pueblos built into the base of a natural canyon wall.

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

This church on a Tohono O'Odham reservation has stood since 1797.